Securing device for tooth implants

ABSTRACT

The invention relates to a accusing device (11) for the durable, hard-wearing and reliably scaled arrangement of tooth implants (31). It has an implant body (10) insertable into a prepared drilling in the jawbone and having an axial threaded blind hole (14) for the insertion of a securing screw (16) to accept a crown or bridge body (31). On the annular face (18 or 28) of the screw head (26) and the implant body (10) there is a concentric annular sealing edge (19 or 30) which, when the crown or bridge body (31) is clamped, enters corresponding annular surfaces thereon and thus provides the required seal.

BACKGROUND OF INVENTION

The invention concerns a securing device for dental implants.

A securing device of this type is known from Canadian Patent 1,313,597(FIG. 6).

With this design, the screw connection for securing a crown or bridge onthe implant body is designed in two parts. One part forms a screw thatcan be screwed with its threaded shaft into a central threaded holedrilled in the implant body and it also has a bent thread-freecylindrical shaft part onto which a sleeve-like socket can be placed tosecure it. With a peripheral face part that tapers conically toward thebottom, the cylindrical shaft part is supported on a complementaryinside ring-shaped shoulder of the securing socket, so the socket andthe implant body can be secured together axially.

Between the two parts there is a ring gasket whose lower ring facereceives a concentric ring-shaped sealing edge that is provided on theupper ring face of the implant body so as to form a seal.

Another seal is provided in the form of a ring gasket that is insertedin a peripheral groove of the cylindrical shaft part of the connectingscrew and is supported on the inside circumference of the sleeve-likesecuring socket.

The other part of the screw connection is formed by an anchoring screwthat can be screwed with its threaded shaft into a central threaded holein the cylindrical shaft part of the connecting screw. The anchoringscrew serves to axially secure a receptacle part for a dental prosthesisin the form of a crown or a bridge, which also forms the upper cap partof the sleeve-like securing socket.

Therefore, the anchoring screw has a screw head that tapers conicallytoward the lower end and is supported on the inside peripheral part of acentral cylindrical drilling in the receptacle part with a matchingconical taper.

The receptacle part in turn sits securely in a crown or bridge that canbe secured on the socket base by tightening the anchoring screw.

The arrangement of the sealing devices explained here (O ring; ringgasket and sealing edge) prevents the seepage of oral fluids that mightlead to an infection into the implant body.

The type of seal described here is formed by the multi-part and thusexpensive design of this securing device.

SUMMARY OF INVENTION

The object of this invention is to provide a securing device that willassure a tight reliable seating of crowns or bridges on post-likeimplant bodies without requiring any additional special sealingelements.

Due to the fact that the ring-shaped faces of the screw head and theimplant body are each provided with a ring-shaped sealing edge, aform-fitting mutual meshing of these ring-shaped faces with a crown orbridge is achieved because when the securing screw is tightened itproduces a high surface pressure leading to plastic deformation of thering-shaped face of the crown or bridge supported on the respectivesealing edge. This levels out the pits and cavities remaining betweenthe ring-shaped faces that are to be tightened to each other.Accordingly, this yields a connection of the parts joined that remainsabsolutely tight over a period of time.

This invention makes it possible to attach a crown or a bridge directlyto the implant body without having to use any additional sealing agentsand thus it greatly simplifies the overall design.

German Utility Patent 8,905,497.0 has already disclosed a securingdevice for dental implants having a shell-like prosthesis anchoringdevice that can be screwed onto an implant body to be implanted in thejawbone. On its lower ring-shaped face which has a threaded shaft, theprosthesis anchoring device has a concentric collar with a peripheralface that tapers conically toward the outside.

When the anchoring device is screwed in place, however, it does not siton an inside ring-shaped shoulder of the crown or bridge as in theinvention but instead it rests on the implant body itself.

The ring-shaped sealing edges provided according to this invention canbe designed as part of the corresponding part by turning it on a latheor by some other suitable method.

A preferred embodiment of the sealing edges is disclosed. Structure isalso provided to promote the bonding of the material can be implementedon the end faces of the sealing edges with regard to the plasticdeformation of the material to be accomplished.

It is also favorable if a strength gradient is provided with regard tothe desired plastic deformation of the material with respect to theparts to be joined together.

In another advantageous embodiment of the invention, the securing screwhas features to maintain a permanent seal.

Such a design of the securing screw makes it possible to achieve a greatincrease in its potential axial elasticity, which results in an increasein edge pressure of the meshed threads of the threaded shaft of thesecuring screw and the inside thread of the implant body and helps tomaintain this pressure.

Depending on the structural height of the implant, it is advisable todesign the length of the thread-free part of the shaft of the securingscrew and the diameter of the screw head and provide a shaft threadaccording to the particular details described herein.

The pairing of materials between the securing screw and the bridge orcrown and/or the implant body may be either lubricated or notlubricated. If lubricated, a significant increase in axial grippingforce by minimizing the friction acting between the flanks of thethread.

The securing screw in the embodiment claimed here can be used to equaladvantage for implants with a design that is bent or coaxial with theimplant bodies.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures illustrate one embodiment of a securing device according tothis invention, where they show the following:

FIG. 1: shows the implant body of the securing device, shown partiallyin a longitudinal sectional view;

FIG. 2: shows the securing screw that can be screwed into the implantbody for mutually securing the implant body and the crown or bridge,shown in preferred dimensions;

FIG. 3: shows a detail on a larger scale than FIG. 2, represented by adash-dot circle;

FIGS. 4 and 5: each show a cross section through variants of the sealingedge, where these also apply to the sealing edge of the implant body;

FIG. 6: shows a longitudinal section through a securing device holding adental crown; shown in a shortened diagram.

BEST MODE FOR CARRYING-OUT THE INVENTION

The implant body of the securing device 11 is designated as a whole as10 in FIG. 1 and is designed as a circular cylinder in cross section. Ithas an axial blind hole 12 with an inside thread 14 cut in the area ofthe base of the blind hole for screwing in the securing screw 16illustrated in FIG. 2. With the help of this screw, a conventional crownsuch as that illustrated in FIG. 6 can be secured to the upperring-shaped face 18 of implant body 10, for example. A ring-shapedsealing edge 19 is provided concentrically on the ring-shaped face 18 ofthe implant body 10.

A hexagonal shape molded on the periphery in the area of ring-shapedface 18 is labeled as 20 and serves to secure the implant structures toprevent further rotation.

The thread-free shaft part 22 of the securing screw 16 is several timeslonger than its threaded shaft 24, which preferably has an M2 thread.The height of screw head 26 corresponds approximately to the diameter ofshaft part 22.

With a ring-shaped sealing edge 30 attached concentrically to thering-shaped face 28 of the screw head 26, the latter is supported on acorresponding inside ring-shaped shoulder 33 when the crown or bridgebody 31 is tightened in place (see FIG. 6).

According to FIG. 3, the sealing edges 19 and 30 preferably have atrapezoidal cross section with the following preferred dimensions:

Base width a: 0.10 mm

Width of flat ring-shaped face 32: 0.04 mm

Height of sealing edge c: 0.05 mm

Radial distance d of sealing edge 30 from the outside periphery of screwhead 26 or the implant body (FIG. 4): 0.05 mm

It should be pointed out here that the diagrams of the sealing edges 19and 30 according to FIGS. 3-5 do not correspond to the precisedimensions given here.

Although the ring-shaped face 32 of sealing edges 19 and 30 according toFIGS. 2 and 3 is designed to be flat, the displacement of material alongthe inside ring-shaped shoulder 33 of a crown or bridge that takes placeunder the influence of the tightening force in effect when tighteningthe securing screw 16 can be further promoted by the fact that the twoboundary zones of ring-shaped faces 32 of sealing edges 19 and 30 arerounded, as illustrated in FIG. 4, and ring-shaped faces 32 arethemselves designed with a slight convex curvature or, as shown in FIG.5, with an at least approximately curved shape in cross section.

The securing screw preferably has the following specifications:

Length of threaded shaft 24: 1.60 mm

Pitch of the shaft thread: 0.40 mm

Length of thread-free shaft part 22: 5.00 mm

Diameter of thread-free shaft part: 1.50 mm

Height of the screw head 26: 1.50 mm

Outside diameter of the screw head 26: 2.50 mm

Inside diameter of the screw head: 2.10 mm

Flank diameter of the thread: 1.74 mm

Core diameter of the thread: 1.50 mm

Stress cross section of the thread-free part 22 of the shaft: 1.77 mm²

Interfacial pressure: 1000 N/mm²

Material of the securing screw 16: Ti6 Al 4V

Material number: 3.7165

Yield point: 1050 N/mm²

Tensile strength: 1140 N/mm²

Modulus of elasticity: 106,000 N/mm²

Elongation at break: 15%

Reduction of area 40%

Endurance at 1,000,000 load cycles: ±230 N/mm²

Assembly torque of securing screw 16: 30 Ncm

Securing screw 16 which conforms to these specifications ischaracterized by appropriate bending softness, a great axial elongationlength and accordingly a settling loss which turns out to be negligibleif a proper tensile stress that can be produced by the stated assemblytorque is selected for mutual tightening of implant body 10 and a crownor bridge body 31 and thus the crown or bridge remains at tightly seatedwithout being subject to any external influence.

As FIG. 6 shows, the crown body 31 includes a tooth body 34 made ofceramic, for example, and applied to a structural shell 36 of a crownsupport 38.

When crown body 31 is tightened onto implant body 10, structural shell36 is at first supported with a lower outside flange 40 on sealing edge19 of the upper ring-shaped face 18 of implant body 10, and screw head26 of securing screw 16 rests with its sealing edge 30 on the insidering-shaped shoulder 33 of structural shell 36.

The tension forces acting axially here cause the sealing edges 19, 30 tocut into the ring-shaped face of outside flange 40 or inside ring-shapedshoulder 33 until the ring-shaped faces that face each other are incontact. This is made possible by the fact that the crown support 38 ispreferably made of gold and therefore there is a strength gradientbetween this part and the parts 10 and 16 that are made of titanium.

Sealing edges 19, 30 guarantee a satisfactory radial seal with respectto axial blind hole 12 of implant body 10.

Structural shell 36 is also sealed by a plastic filling 42, where apellet 44 of foam is introduced between the filling and screw head 26 ofthe securing screw 16 to keep the internal polygonal shape of screw head26 free of plastic so that crown 31 can be removed from implant body 10at any time.

I claim:
 1. A securing device for dental implants, with a securing screw(16) having a threaded shaft (24); and a post-like implant body (10)that can be inserted into a prepared drilling in the jawbone, theimplant body having an axial blind hole thread (14) for inserting thethreaded shaft (24) of the securing screw (16) to mount a crown or abridge (31), which crown or bridge (31) is provided with an insidering-shaped shoulder (33), and for securing the crown or bridge (31) onthe implant body (10) the implant body further having a ring-shaped face(18), with a first ring-shaped sealing edge (19) provided on thering-shaped face (18) facing the crown or the bridge (31); the securingscrew (16) having a screw head (26) having a ring-shaped face 28 thatengages the inside ring-shaped shoulder (33) of the crown or the bridge(31) characterized in that a second, opposing ring-shaped sealing edge(30) provided on the ring-shaped face (28) of the screw head (26) of thesecuring screw (16), and the ring-shaped sealing edges (19, 30) eachdirectly engage the ring-shaped shoulder (33) on the structure (38) ofthe crown or bridge (31),the material of at least the implant body andthe screw being harder than the material of the inside ring-shapedshoulder of the crown or bridge, each of the sealing edges extendingfrom its respective face, so that upon positioning of the crown orbridge on the structure (38) and tightening down of the screw, theinside ring-shaped shoulder of the crown or bridge becomes axiallyengaged between the sealing edges, and the sealing edges press intoopposed surfaces of the inside ring-shaped shoulder, causing plasticdeformation thereof to form a seal.
 2. Securing device according toclaim 1, characterized by a trapezoidal cross section of the sealingedges (19, 30).
 3. Securing device according to claim 2, characterizedby the following dimensions of the trapezoidal sealing edges (19, 30),as seen in cross section:base width a: 0.10 mm, width of flatring-shaped face b: 0.04 mm, height of sealing edge c: 0.05 mm, radialdistance d of sealing edges (19 or 30) from the outside perimeter of thepart (10 or 16) carrying them: 0.05 mm.
 4. Securing device according toclaim 3, characterized by rounded inside and outside ring-shaped edgesof the ring-shaped face (32) of the sealing edges (19, 30).
 5. Securingdevice according to claim 3, characterized by a ring-shaped face (32) ofthe sealing edges (19, 30) with a convex curvature in cross section. 6.Securing device according to claim 1, characterized by a greatermaterial strength of the part (10 or 16) carrying the sealing edges (19,30) in comparison with the strength of the crown or bridge to beattached to it.
 7. Securing device according to claim 1, characterizedby the following features:a) the length of the threaded shaft (24) ofthe securing screw (16) is between 1.00 mm and 2.00 mm; b) the pitch ofthe shaft thread is between 0.2 mm and 0.6 mm; c) the thread-free part(22) of the shaft has a diameter between 1.00 mm and 2.00 mm; d) thelength of the thread-free shaft part (22) is greater than the maximumlength of the threaded shaft (24); e) the height of the screw head (26)is between 1.00 mm and 3.0 mm.
 8. The securing device according to claim7, wherein the length of the threaded shaft (24) is 1.60 mm.
 9. Thesecuring device according to claim 7, wherein the pitch of the shaftthread is 0.4 mm.
 10. The securing device according to claim 7, whereinthe thread-free part (22) of the shaft has a diameter of 1.50 mm. 11.The securing device according to claim 7, wherein the height of thescrew head (26) is 1.5 mm.
 12. Securing device according to claim 1,characterized by a length of the thread-free shaft part (22) between3.50 mm and 14.00 mm, preferably 5.00 mm.
 13. The securing deviceaccording to claim 12, wherein the length of the thread-free shaft part(22) is 5.00 mm.
 14. Securing device according to claim 1, characterizedby a screw head diameter between 2.00 mm and 3.00 mm, preferably 2.50mm.
 15. Securing device according to claim 1, characterized by an M2thread (24).
 16. The securing device according to claim 1 wherein thesealing edges have a substantially trapezoidal configuration incross-section.
 17. The securing device according to claim 1 wherein thesealing edges are substantially concentric relative to one another. 18.A securing device for dental implants, for use in combination with acrown or bridge body, having a crown support having an insidering-shaped shoulder with two axially opposed faces, and a boreextending axially through the crown support, the securing devicecomprising:an implant body, having an axially extending blind boretherein, a portion of the bore being internally threaded, the implantbody further having an annular face surrounding the opening of the blindbore, an axially extending sealing ridge emanating from the annular faceand positioned to axially engage one of the axially opposed faces of acrown support of a crown or bridge body, when a crown or bridge body ismounted onto the securing device; a screw, having a shaft with threadedand non-threaded portions and a screw head, an annular face on the screwhead, an axially extending sealing ridge emanating from the annular faceof the screw head and positioned to axially engage the other of theaxially opposed faces of a crown support of a crown or bridge body, whena crown or bridge body is mounted onto the securing device; the implantbody and the screw being fabricated from a material which is harder thanthe material from which the crown support of a crown or bridge body isfabricated.